Abstract
BACKGROUND: Some studies have shown a relationship between seasonality in weather patterns and depressive and behavioural disorders, especially in temperate climate regions. However, there is a lack of studies describing the seasonal patterns of hospital admissions for a variety of mental disorders in tropical and subtropical nations. The aim of this study has been to examine the relationship between seasons and daily hospital admissions for mental disorders in Hanoi, Vietnam. DESIGNS: A 5-year database (2008-2012) compiled by Hanoi Mental Hospital covering mental disorder admissions diagnosed by the International Classification of Diseases 10 was analysed. A negative binominal regression model was applied to estimate the associations between seasonality and daily hospital admissions for mental disorders, for all causes and for specific diagnoses. RESULTS: The summer season indicated the highest relative risk (RR=1.24, confidence interval (CI)=1.1-1.39) of hospital admission for mental disorders, with a peak in these cases in June (RR=1.46, CI=1.19-1.7). Compared to other demographic groups, males and the elderly (aged over 60 years) were more sensitive to seasonal risk changes. In the summer season, the RR of hospital visits among men increased by 26% (RR=1.26, CI=1.12-1.41) and among the elderly by 23% (RR=1.23, CI=1.03-1.48). Furthermore, when temperatures including minimum, mean, and maximum increased 1°C, the number of cases for mental disorders increased by 1.7%, 2%, and 2.1%, respectively. CONCLUSION: The study results showed a correlation between hospital admission for mental disorders and season.